The term 'not professional' can be described in three different ways: UNPROFESSIONAL (14 letters), amateur (7 letters), and LAY (3 letters). UNPROFESSIONAL is an adjective used to describe someone who does not act in a professional manner, often due to lack of experience or training. Amateur is also an adjective used to describe someone who is not a professional, but it implies that the person is doing something for fun or as a hobby. LAY is a noun used to describe someone who is not a professional or an expert in a particular field.